I was on that for seven years and
finally got a sensitivity to it and
it was no longer effective. With autoimmune urticaria vs. chronic idiopathic urticaria (which they said was what i had for eight of the ten years) I couldn't use antihistimines at all with effect, doxepin was the only one!
Plaquenil is our next option. However using synthroid (synthetic thyroid) daily has done more for my hives than anything used thus far.